Water In Plants Flashcards
Diffusion
The movement of molecules from a region of high concentration to one of lower concentration
Osmosis
A type of diffusion in cells
When a substance crosses a semipermeable membrane -> Water ofr other solvents
Doenst need any energy
Solvents
A molecule that has the ability to dissolve other molecules (Solutes)
The solution is homogenous and cant be seperatet physically
Semipermiables
A layer only certain molecules can pass through
They filter solutions coming ointo a cell
A semipermeable membrane is usually created by to phospholipid layers -> a lipid that is attached to a polar head
Turgidt
Cells or tissues that are swollen from water uptake
Some cells lyse or split open when they become too turgid.
Tugor pressuret
The force exerted by stored water against a cell wall
Pressure potentialp
In turgid plant cells it has a positive value
In Xylem cells it is negative so it can transpirate
Imbition
when When a plant cell absorbs water by surface attraction
Active Transport
Active transport is the process of transferring substances using energy
Cohesion-tension Theory
The theory, that the water scent in trees is exclusively due to the transpirational pull from continous water columns in the xylem conduit running from the roots to the leafs
Regulation of Transpirationr
Plants regulate their transpiration by controlling the size of their stomata
Hydathodes
A type of pore
Commonly found in angiosperms
Secretes water through the epidermis
Guttation
The excretion of xylem from the edges of the leaves and other vascular parts due to increased levels of water in the soil at night, when the stomata are closed
Pressure-flow Hypothese
The best supportet theory of sap flow through the phloem.
High concentration of sugar in a plant part creates a osmosis gradient -> water from the adjacent xylem gets drawn into the cell -> a tugor pressure (hydrostatic pressure) is created
This causes the sap to not only flow upwards but downwards
Essential Elements
Hydrogen
Carbon
Nitrogen
Oxygen
-> make up 99% of the protoplasm
